One of the manufacturing problems in modern day aircraft is the placement of the bundles of electrical wire which are distributed throughout the aircraft. Quite commonly, a number of relatively long lengths of wire are grouped together in a bundle and tied at regularly spaced intervals along their length. This enables the bundles to be pulled through the aircraft structure to the appropriate locations. This tying is commonly accomplished simply by a manual operation, where a person ties a short length of string around the bundle. The flexible string makes a reliable tie, and as the bundle is pulled through the aircraft, the string tie is not prone to catch on the aircraft structure. However, this manual operation of making numerous ties for the many bundles of wire is time consuming and thus rather expensive.
Accordingly, there have been various attempts to make automated bundle ties. One approach has been to use plastic straps with mechanical locking devices. However, the plastic straps have a knob which is objectionable when these wire bundles are installed because the knobs catch or hang up as they are passed through the holes during installation. Another objection is that the knobs tend to abraid adjacent wire bundles.
Another prior art approach has been to develop a lace tape tie applicator using ultrasonic energy to bond the tie. However, to the best knowledge of the applicants, the ties produced by the ultrasonic tie gun are somewhat lacking in that they are sometimes not sufficiently tight and sometimes have poor bond strength. There have been in the prior art various devices which use moderately stiff wires which are wrapped around the bundle and then twisted to form a tie. However, these also have a drawback in that such ties tend to catch or hang up on the structure as the bundle is pulled through holes, and these also can abrade adjacent wires.
A search of the U.S. patent literature has disclosed a number of patents relating to various tying devices, and these are discussed briefly below.
U.S. Pat. No. 54,810, Adams, shows a bale tying device having a rotatable member which engages two members to cause these to move oppositely to one another and tighten a hoop that is placed around the bale.
U.S. Pat. No, 587,926, Bates et al, shows another bale tying device which stretches a wire and cuts it. It then forms a loop in the rear end of the wire so that the wire can be tied.
U.S. Pat. No. 774,226, Wiseburn et al, shows a mechanical device which grasps two ends of a binding tape and pulls these tight.
U.S. Pat. No. 1,784,025, Norton, shows a device for stretching a strap which has previously been placed around a package.
U.S. Pat. No. 3,033,102, Friyklund, shows a cable lacing machine where the lace is fed by a needle to a gripper and then pulled around the bundle. The gripper and needle are then rotated to make a tie, and an electrode is moved down to squeeze the knot and also make a weld.
U.S. Pat. No. 3,118,365, Rollo et al, shows an apparatus where a strip is placed along the length of the wires which are to be bound. A tie is made around the wire bundle and over the strip. The strip has a conductor placed therein to enhance the electrical conductivity at the location of the tie and thus aid in creating heat to cause a bond.
U.S. Pat. No. 3,154,114, Bailey, shows a hand tool to grip, tension, and then cut a strap which has already been placed around a bundle of wires.
U.S. Pat. No. 3,179,128, Price, shows a hand tool to fasten a strap. One end of the strap is placed on the tool and the other end is wrapped around the wire bundle. Operation of the tool pulls the strap and pushes it down to a fastening position.
U.S. Pat. No. 3,250,209, Gage et al, shows a device for wrapping a strand around a bundle of wires. The strand is fed through a curved element having an interior groove to accommodate the strand, until the strand engages a stop. An arm then moves down to clamp the strand, after which the strand is tightened. Then the ends of the strand are stapled together and the strand is cut to complete the tie.
U.S. Pat. No. 3,269,300, Billett et al, shows a strapping machine where a plastic strap is force fed through a yoke which surrounds the article which is to be strapped. The apparatus then tensions the strap to pull it out of the yoke, and a heating element is moved adjacent to overlapping parts of the strap. A cam actuated member pushes the overlapping straps against the heating element, and the heated strap portions are held together until cooled to complete the bond. The strap is then cut.
U.S. Pat. No. 3,348,584, Beach, shows a hand tool to grip two end portions of a strap that has previously been placed around an object and inserted in a buckle. The tool is pivoted to tighten the strap.
U.S. Pat. No. 3,368,590, Welden, shows a wire tying machine where a piece of wire is directed through a track to form a 270.degree. arc around a group of rods which are to be tied. Then the loop ends are engaged by a twister to form a tie.
U.S. Pat. No. 3,466,847, Farkas, shows a device where a bundle is moved through a set of open jaws and a tape is placed between the jaws. The jaws are closed to form a bond on the tape.
U.S. Pat. No. 3,489,076, Countryman, shows a device where a strap is pushed through a loop member around a bundle of wires. The overlapping ends of the loop are bonded one against the other.
U.S. Pat. No. 3,527,157, Elineau, shows a device where a ring rotates around a bundle to wrap wire around the bundle. The wire is unwound and carried by a pulley mounted on the wheel. There is a cutter and twister to tie the ends of the wire in a twisted pattern.
U.S. Pat. No. 3,589,406, Moverg, discloses a hand tool for tightening a shackle that is placed around the neck of a bag.
U.S. Pat. No. 3,633,633, Countryman, shows a device where a pair of jaws are opened to receive a wire bundle. The jaws are then closed, and a ribbon is fed in a guide in the jaws around a bundle. Then the ribbon is twisted to join the ends of the ribbon together.
U.S. Pat. No. 3,648,739, Angerola, shows a strap clamping and severing assembly where the strap is manually placed around the article, and the device tightens, bonds, and severs the strap.
U.S. Pat. No. 3,665,845, Lyon, illustrates a rotatable ring that is positioned around the object to be tied. The ring has four retractable fingers which carry a tape around the package. The fingers are retracted, the tape tightened, and a heating element bonds overlapping portions of the tape. A knife then cuts the tape.
U.S. Pat. No. 3,669,799, Vilcins et al, shows an apparatus where a strap is manually placed around a package, after which the device tightens and bonds the strap.
U.S. Pat. No. 3,771,436, Sato, discloses a specific mechanism for bonding a strap which has been placed around an article.
U.S. Pat. No. 3,830,263, Benfer, discloses a tool for applying a strap, where the strap is placed around a wire bundle, and then the end of the strap is inserted in the hand tool to be tightened. This same general type of hand tool is also shown in U.S. Pat. No. 3,865,156, Moody et al.
U.S. Pat. No. 4,094,342, Nishikawa et al, shows an automatic binding device where a bundle is placed in a ring-shaped guide member. The tying string or wire is fed through the guide member to form a tie around the bundle.
In view of the foregoing, it is an object of the present invention to provide a method and apparatus for effectively and reliably forming a tie around a bundle of wires, and particularly for applying a tie around a bundle of wires which are to be mounted in an aircraft.
It is a further object to provide an apparatus which can be incorporated in a portable hand carried tool and which can be operated at relatively high speeds to form the tie, and also to form a bond.
It is also an object to provide the apparatus and method where a heated bonded member can adequately perform its bonding operation, in a manner to be self-cleaning.